The organization of repeated DNA elements interspersed with insertion-like sequences has been studied in D. melanogaster. These interspersed elements were shown to be homologous to sequences located on different chromosomal sites in different stocks of D. melanogaster, suggesting that the sequences are transposable in the genome. One such transposable element, named 101F, has been analyzed further. We have shown that it is a member of a divergent family of sequences, does not carry long terminal repeats, and that its insertion leads to a duplication of 13 base pairs at the target site. These properties define a new class of transposable sequences in Drosophila.